In 2015, at COP21, governments invited the IPCC to prepare this special report. It was approved by delegates from all governments in October 2018, on the basis of the assessment performed by 91 authors from 40 countries, with 133 contributors, of 6000 publications, after 3 rounds of review (1131 reviewers, more than 42 000 review comments). This report provides the current state of global warming, with 1°C due to human activities; the consequences of an additional half a degree or one degree of global warming; the greenhouse gas emission trajectories consistent with stabilisations at 1.5°C or 2°C; the systems transitions, with an assessment of 6 dimensions of feasibility; the multiple intersections with sustainable development goals. This report is so stimulating that governements could not find words to receive it. In December 2018, at COP24, four of them (Saudi Arabia, Kuweit, USA and Russia) refused to welcome it. The COP24 decision expresses its appreciation for the work done, welcomes the timely completion of the report, and invites parties to make use of it...

Dr. Valérie Masson-Delmotte is a senior scientist from Laboratoire des Sciences du Climat et de l'Environnement, Institut Pierre Simon Laplace. She is the Co-chair of IPCC Working Group I for the AR6 cycle. Her research interests are focused on quantifying and understanding past changes in climate and atmospheric water cycle, using analyses of natural archives such as ice cores, and climate modelling for the past and the future. She has worked on issues such as the North Atlantic Oscillation, drought, climate response to volcanic eruptions, polar amplification, climate feedbacks, abrupt climate change and ice sheet vulnerability accross different timescales and she has published more than 250 scientific publications (h index 63), including, this year : «Choosing the future of Antarctica», Nature, 2018 and «Six research priorities for cities and climate change», Nature, 2018. She is active in outreach for children and for the general public and has contributed to several books on climate change issues (e.g. Greenland, climate, ecology and society, CNRS editions, 2015). Her research was recognized by several prizes (European Union Descartes Prize for the EPICA project, 2008; Women scientist Irène Joliot Curie Prize, 2013; Tinker-Muse Prize for science and policy in Antarctica, 2015; Highly Cited Researcher since 2014), as well as her outreach activities (Prix Jean Perrin 2015, Société française de physique).